This is at it’s heart an update to RHEL 5. But Redhat is promoting it as “the first product to deliver commercial quality open source virtualization featuring Kernel-based Virtual Machine (KVM) hypervisor technology.” The kernel version is still 2.6.18, with backported patches. Redhat is promoting upcoming Red Hat Enterprise Virtualization products along with RHEL 5.4
keep reading Redhat Enterprise 5.4 Released